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When we were planning our RV adventures and Full Time RV life I knew we would want, and need to boondock (Dry camp with no hookups) to lower the cost of living. We have an onboard generator that would run everything but it uses 1 gallon of gas per hour. That would cost us around $32/day to keep the fridge running and charge our phones and laptops. At the rate we would be broke and might as well stay in a campground. This led me into researching solar energy.
I knew the basics of solar power. You need to have solar panels, a battery, and an inverter. But what did all of that mean? How did it tie in together? And how much of it would I need? These were the questions I did not have an answer for just like many who are curious about solar power. After over a month of research I was ready to put it all together. Continue reading to learn about solar power, how it helps us boondock, and where and what to buy.
The basics of solar energy is like an automobile (car). The solar panels absorb energy (gas), then the energy travels through the electric wiring (fill valve) to your battery bank (Fuel Tank). The batteries store the enegery (gas) until the inverter (engine) needs it to run. The power inside the RV will only last as long as the batteries (gas tank) has energy (gas) stored in it. Now that we know the basics of solar power, and how it works lets get into the components.
Solar panels come in many shapes and sizes as well as different silicon crystals. The best on the market currently is the polycrystaline solar panels. The also come in various watts from 25 and up. The most common are the 100 watt panels. These are what we use. They produce 5.29 amps an hour in the best sunlight. This is around 5 hours per day. They will produce some amps during the other hours but it isn’t optimal. So one panel will produce approximately 26 amps per day. This number will come into use when you know how many amps you use.
The Charge controller is the brain of the solar power distribution. It reads how many volts, watts, and amps are coming in then sends out the correct amount of power to the batteries to keep them charged. A good controller will actually lower the amount of power going to the batteries to keep them topped off, while other controllers will just turn off when batteries are fully charged. There are 2 types of solar charge controllers, pwm and mppt. The pwm has to have the same voltage input and output where the Mppt will adjust the output voltage according to the battery bank. Charge controllers also have a variety of amp sizes from 5 amps and up. You will need to size yours accordingly.
We bought the Renogy 400 watt kit that comes with 4 100 watt solar panels, the charge controller, brackets, fuse, and some wiring. You will need to buy longer MC4 cable for you solar panel hook up. Click on the image below to go to the product page for more info.
The Battery Bank
The size of your battery bank will depend on your electricity usage. When we boondock we are very conservative with our electric so we are able to use a smaller bank. Remember this is where all the energy is stored so the bigger the bank the more days you can run without sun. Batteries come in all kinds of forms and prices. Some people will pay $1500 per battery. We didn’t have that kind of money to spend so I found the best budget friendly battery for us is the Duracell G2 golf cart battery. These cost $129.99 plus a $21.99 core charge if you do not have an old battery to exchange. They have 235 amp hours meaning if you pull 1 amp per hour it will last 235 hours. However, this is a lead acid battery which doesn’t like to drop below 50% charge, so you have 117.5 amps available to use. These are 6 volt batteries so you will need 2 of them to make 12 volts.
The way these get wired is called a series parallel. You tie 2 together in series to make 12 volts. When working with series, volts get added together and amps stays the same. Then to increase the amount of amps we can use, we add 2 more batteries in parallel. When working with parallel, volts stays the same and amps get added together. To build your battery bank bigger you will keep adding a set of 2 batteries in parallel until you have enough amps.
There are 2 forms of power from an inverter, Pure Sine and Modified Sine Wave. If you will be powering expensive electronics or motorized appliances such as a residential fridge you will want to go with the Pure Sine. A pure sine wave inverter is most like standard house electric with curved waves. A modified sine wave works like a step and is a choppy form of electric. It has been known to fry motors and make high end electronics buzz.
The Size of inverter you will need will depend on how many watts you will use at any given time. When using appliances, you will need to factor in startup watts such as that of a residential fridge. You should also look at one with a converter charger built in for charging from the generator or shore power. We have the Aims 1000 watt inverter with a 25/55 amp converter charger. Click on the image below to see more images and learn more about the inverter charger.
So now you know what solar power is and how it works. The only thing left is how much equipment you need. Because boondocking is so fun, I created a spreadsheet that will automate everything for you to help you get started. All you need to enter is the name of the appliance, how many watts it uses and how many hours a day you use it.